The main downside to open source monitoring platforms is that they can be more difficult to deploy and manage. As a result, the indirect staff costs required to run them might be higher. It might also be difficult to obtain professional support for the tools, though many are backed by commercial companies that offer support services for a fee. Lastly, their maturity can vary greatly, and some are not as feature-rich as others.
A handful of open source cloud monitoring tools are mature and ready for production use. Consider the following five options -- discussed in no particular order -- when building a cloud monitoring strategy based on open source software.
First released in 2001, Zabbix is a tried-and-true monitoring tool with highly flexible configurations. It can collect cloud monitoring data using agents, which may be useful when monitoring cloud-based VMs. It also integrates with services like Amazon CloudWatch to collect metrics directly from cloud environments.
Zabbix can be somewhat difficult to set up, especially for monitoring cloud environments. It originated long before anyone was talking about the cloud, so it wasn't designed to be simple to deploy as a cloud monitoring tool. Zabbix's ability to scale is also limited: It only supports up to 1,000 nodes.
If you need a highly customizable monitoring tool for small- to medium-sized cloud environments, Zabbix is a great fit. But it may be harder to work with than the other tools listed here, and it can't scale to support large environments.
Nagios has many similarities to Zabbix. It's been around for more than 20 years, making it a well-established monitoring tool. And it offers the same level of flexibility in terms of configurations and data collection.
A major difference between the two is that Nagios is available in two versions. Nagios Core is free, while Nagios XI is a paid platform that offers enhanced usability and extra features. Nagios' dual-version model may be attractive if you think you might need more features than the free platform provides but aren't sure when first choosing a tool. In that case, start with Nagios Core and upgrade to Nagios XI if necessary later.
If you need more features than Nagios Core offers but don't want to upgrade to Nagios XI, consider Icinga. Created in 2009 as a fork off of Nagios, Icinga offers many of the same features as Nagios Core but adds other capabilities to simplify monitoring and increase usability with features such as a more intuitive interface.
However, Icinga relies on APIs and plug-ins to integrate with a limited number of cloud services and monitoring tools. It can be cumbersome for monitoring certain types of cloud services and lacks the extensive documentation of popular tools like Nagios.
Grafana, which dates back to 2014, is a monitoring tool designed for the cloud age. Technically speaking, Grafana is for the most part a visualization tool. It needs to integrate with other tools to collect data, which it then displays in ways that simplify interpretation.
While this might seem to be a limitation, it is, in many respects, a strength because Grafana provides a great deal of flexibility in selecting a data collector. You can use another open source tool, such as Prometheus, to collect data, or you can import it directly from a cloud service.
Grafana's biggest limitation is that it requires substantial setup effort.
Still, it stands apart from most other open source cloud monitoring tools because it was built first and foremost for the cloud. And it arguably comes the closest to delivering a seamless experience that is comparable to that of commercial alternatives.
Although Zenoss is slightly older than Grafana, it has also evolved into a cloud-focused monitoring tool. Not only does it monitor a variety of cloud services, but it also has predictive AIOps features designed to help teams understand what will happen in the future to prevent service disruptions and scale as needed.
Zenoss Community Edition, the free, open source version of the platform, was discontinued in 2022 and replaced with Zenoss Developer Center, which focuses mostly on building integrations and add-ons for the core paid product, Zenoss Cloud.